As the title suggests, this is the story behind the character Blok. Until the previous storyline he had been a member of the League of Super-Assassins, but had reformed and helped the Legion, and was now trying out for membership in the group, in competition with three of the blandest super-hero wannabes you can imagine, Lamprey, Nightwind and the Crystal Kid. I don't even think anyone in that group made the Legion of Substitute Heroes. During downtime during the tryouts, Blok explains that his race of rock-like beings were native to a planet colonized by humans, and lived peacefully with the humans until their sun went nova. He and the other members of the League of Super-Assassins were children at the time, and somehow managed to mis-interpret the Legion helping to evacuate their people as the Legion causing the death of their planet, and swore vengeance. If you think that's an implausible mess of a story, it gets worse if you know more about LSH history. Anyway, Blok's story warms even cynical Wildfire's heart, and then the team is called to capture some escaped criminals known, swear to god, as the Starburst Bandits, who are breaking into a zoo to steal their fire-haired flying horses. Someone was paid to make this up. The other tryouts think, with some justification, that this is a fake mission meant to test them, and are quickly defeated. I'm not sure what excuse the actual Legion members have for being equally ineffective. Blok, of course, saves the day, and is granted membership in the team.
Sorry for going off at length on the story. I was having trouble believing it myself. Surprisingly, Blok actually became a major member of the team not too long after. Ditko's art wasn't too bad, but nothing really sticks out.
"The Secret Origin Of Blok" J-6846